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Testosterone Total and Free

November 29, 2024Chemical pathologyLab Tests

Testosterone (Total and Free)

What sample is needed for Testosterone?

  1. It is done in the serum.
  2. Can use heparinized plasma.
  3. 24-hours of the urine sample.
  4. Separate the serum immediately; if kept for a more extended period (more than 6 hours), you may get false high values.
  5. The sample is stable at 1 to 4 °C for one week.
  6. Free Testosterone is stable for 1 to 2 days at 4 °C.
  7. At -20 °C, the sample is stable for 6 months.

What are the precautions for Testosterone estimation?

  1. Separate serum from the cells within 6 hours; otherwise, there is a false value elevation.
  2. The level is high in adults in the morning sample and 25% lower in the evening sample.
  3. In females, lower values increase 1 to 2 days mid-cycle.
  4. There are high values after the exercise.
  5. Value is decreased after the overload with glucose.
  6. There is a slow progressive decrease after the age of 50 years.

What are the Indications for Testosterone level?

  1. In males, this test is done to evaluate the following:
    1. Hypogonadism.
      1. This stimulation can be done by giving clomiphene and HCG.
    2. Cryptorchidism.
    3. Impotence.
    4. Pituitary gonadotropic function.
    5. Infertility.
    6. Precocious puberty.
    7. Tumor marker for the testicular tumors.
  2. In the female, this test is done to assess:
    1. Hirsutism and virilizing syndrome.
    2. Ambiguous sex character.
    3. Precocious puberty.
    4. Tumor marker for ovarian tumors.
    5. Maybe it is part of the fertility workup of the chronic anovulatory cycle due to the polycystic ovary.

How will you discuss the Pathophysiology of Testosterone?

  1. Testosterone is the main androgen secreted by the testes and its production increases by puberty.
    1. Women only produce 5% to 10% of the testosterone as much as males.
  2. Androgenic hormone includes:
    1. Dehydroepiandrosterone (DHEA).
    2. Androsterone.
    3. Testosterone.
  3. The adrenal gland produces DHEA, Cortisol, Aldosterone, and Testosterone.
Adrenal androgens

Adrenal androgens

  1. Testes produce DHEA.
  2. Ovaries produce DHEA.
  3. DHEA is a precursor of the Androstenedione precursor of Testosterone and estrogen.
Testosterone synthesis

Testosterone synthesis

  1. Testosterone is responsible for the development of male secondary characters.

What is the mechanism for the Testosterone secretion?

  1. In men, testosterone is secreted by:
    1. Adrenal glands produce 2/3 of the total testosterone.
    2. Testes produce 1/3 of the total testosterone.
  2. In females, testosterone is secreted by:
    1. The adrenal gland is the source of all testosterone in females.
    2. Ovaries also produce some testosterone.
Testosterone source in the female

Testosterone source in the female

  1. Testosterone fluctuation in the level.:
    1. In the male, there is a peak level early in the morning.
    2. The female has cyclic elevation for 1 to 2 days around mid-cycle.
  2. Testosterone is made by:
    1. In males:
    2. In males, it is produced mainly by the Leydig cells, which comprise almost 95% of the total.
    1. In female:
      1. About 50% is made by converting DHEA into fatty tissue.
      2. 30% conversion of DHEA in the adrenal glands.
      3. 20% is made directly by the ovaries.

What is the role of the pituitary gland in Testosterone?

  1. The pituitary gland produces LH in males and FSH in females.
  2. LH  stimulates the Leydig cells to produce  Testosterone.
  3. FSH  Stimulates Sertoli cell to help in spermatogenesis.
Testosterone synthesis in the testes

Testosterone synthesis in the testes

What are the functions of Testosterone?

  1. Testosterone stimulates spermatogenesis and secondary sex character.
  2. Testosterone Increased production is seen in:
    1. In Male produces premature puberty.
    2. Females produce masculinity (manifested by amenorrhea and excessive growth of body hair).
  3. Testosterone exists in two forms in the serum:
  4. In males:
  5. Circulating testosterone is bound to:
    1. 60% to 65% strongly bound to sex hormone-binding globulin (beta-globulin).
    2. 20% to 40% is bound to serum albumin.
    3. 1% to 2% testosterone is free or unbound testosterone. This is the only biologically active testosterone.
  6. In females:
  7. Testosterone fractions consist of:
    1. 1% is free testosterone.
    2. 80% bound to sex hormone-binding globulin (SHBD).
    3. 19% bound to albumin.
  8. The free fraction is 2% unbound to the sex hormone globulin and albumin.

Total testosterone = Bound fraction + Free fraction.

    • Free Testosterone fraction is the Active form.
Testosterone formation and functions

Testosterone formation and functions

How will you discuss Testosterone metabolism?

  1. Testosterone is metabolized in the liver, and the main metabolites are:
    1. Androsterone.
    2. DHT (dihydrotestosterone).
    3. These are further metabolized into androstenedione and etiocholanelone.
    4. End metabolites are excreted through the kidneys.
  2. The main metabolites of adrenal, testicular, and ovarian hormones are secreted through the kidneys as 17-ketosteroids.
Testosterone and role of anterior pituitary gland

Testosterone and the role of the anterior pituitary gland

What is the normal value of Testosterone?

Source 1

Testosterone Free

Age pg/mL
Male Female
Cord 5 to 22 4 to 16
Newborn (1 to 15 days) 1.5 to 31.0 0.5 to 2.5
1 to 3 month 3.3 to 8.0 0.1 to 1.3
3 to5 month 0.7 to 14.0 0.3 to 1.1
5 to 7 month 0.4 to 4.8 0.2 to 0.6
Children
6 to 9 year 0.1 to 3.2 0.1 to 0.9
10 to 11 year 0.6 to 5.7 1.0 to 5.2
12 to 14 year 1.4 to 156 1.0 to 5.2
15 to 17 year 80 to 159 1.0 to 5.2
Adult 50 to 110 1.0 to 8.5
  • To convert into SI units x 3.47 = pmol/L

Testosterone Total (blood)

Age ng/dL
Male Female
Cord 13 to 55 5 to 45
Premature 37 to 198 5 to 22
Newborn 75 to 400 20 to 64
1 to 5 month 1 to 177 1 to 5
6 to 11 month 2 to 7 2 to 5
Children
1 to 5 year 2 to 25 2 to 10
6 to 9 year 3 to 30 2 to 20
Puberty Tanner stage
1 2 to 23 2 to 10
2 5 to 70 5 to 30
3 15 to 280 10 to 30
4 105 to545 15 to 40
5 265 to 800 10 to 40
Adult 280 to 1100 15 to 70
Pregnancy 3 to 4 x adult level
Postmenopausal 8 to 35
  1. To convert into SI unit x 0.0347 = nmol/L

Urine

  • 20 to 50 years
  • Male   = 50 to 135 µg/day
  • Female = 2 to 12 µg/day
    • >50 years
      • Male = 40 to 60 µg/day
      • Female = 2 to 8 µg/day
Source 2

Total testosterone

  • Men = 3 to 10 ng/mL
  • Women = <1 ng/mL
  • Prepubertal boys and girls = 0.05 to 0.2 ng/mL

Source 4

Free testosterone

  • Men = 50 to 210 pg/mL.
  • Women = 1.0 to 8.5 pg/mL.
  • Children:
    • Boy = 0.1 to 3.2 pg/mL.
    • Children Girl = 0.1 to 0.9 pg/mL.
  • Puberty:
    • Boy = 1.4 to 156 pg/mL.
    • Puberty Girls = 1.0 to 5.2 pg/ml.

Total testosterone

  • Men = 270 to 1070 ng/dL.
  • Women = 15 to 70 ng/dL.
  • Postmenopausal women = 8 to 35 ng/dL.
  • Pregnant women = 3 to 4 ng/dL

Testosterone by age:

  1. Serum level of testosterone :
  2. In male infants :
    1. By 2 weeks = around 25 ng/dL.
    2. BY 2 months = around 275 ng/dL.
  3. In female infants :
    1. By 2 weeks = around 25 ng/dL.
    2. By 2 months = Value decreases and remains low throughout early childhood.

What are the causes of Increased values of Total Testosterone?

  1. Male
    1. hyperthyroidism.
    2. Adrenal tumors.
    3. Adrenal Hyperplasia.
    4. Hypothalamic tumor, Pinealoma.
    5. Viral encephalitis.
    6. Testicular or extragonadal tumors where Leydig cells produce testosterone.
    7. Testosterone resistance syndrome.
  2. Female
    1. Adrenal neoplasm.
    2. Hilar cell tumor.
    3. Idiopathic Hirsutism.
    4. Trophoblastic disease during pregnancy
    5. Ovarian tumors
    6. Polycystic ovary.

What are the causes of decreased Total testosterone value in Males?

  1. Klinefelter syndrome.
  2. Pituitary failure leading to hypogonadism.
  3. Hypopituitarism may be primary or secondary.
  4. Orchiectomy.
  5. Delayed puberty.
  6. Down syndrome (trisomy 21).
  7. Cirrhosis.
  8. Cryptorchidism due to undescended testes.

What are the causes of increased Free Testosterone in Females?

  1. Hirsutism.
  2. Virilization.
  3. Polycystic ovaries.

What are the causes of decreased Free Testosterone in Males?

  1. Hypogonadism.
  2. Old age.

Questions and answers:

Question 1: What type of cell is the source of testosterone?
Question 2: Total testosterone is biologically active?
Possible References Used
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